This invention relates to a liquid fuel combustion apparatus, such as a portable heater, in which a wick is moved up and down for thermal power adjustment, ignition, and extinction.
In conventional combustion apparatuses of this type, combustion is sustained by the use of a wick. The wick is a cylindrical body which is formed of knitted fibers and is disposed around a wick guide cylinder for vertical movement. The lower end of the wick is normally immersed in liquid fuel. During combustion, the wick is elevated so that its upper end is located in a combustion region over a pan portion. In this position, the upper end portion of the wick is ignited for continued combustion. Thermal power is adjusted by vertically moving the wick. A satisfactory combustion condition can be obtained by moving the wick within a proper range. Normally, the proper range is as little as 5 mm or so. Therefore, it is guite possible that the wick will be excessively lowered, which will cause incomplete combustion to take place and produce an offensive smell or a great deal of carbon monoxide, or generate tar, which will stick to the wick.
A flame on the wick is extinguished by completely lowering the wick out of the combustion region. The vertical moving range of the wick for thermal power adjustment is normally about 5 mm, and the downward displacement of the wick for extinction is several times as long as vertical moving range. Conventionally, a common dial mechanism is used both for thermal power adjustment and for extinction. In completely lowering the wick for extinction, therefore, the dial must be turned a number of times, thus complicating the operation of the apparatus. Such a troublesome extinction operation sometimes induces an operator to leave the wick midway without lowering it fully to the extinction position. As a result, the fire cannot be completely extinguished, and a bad smell may be produced.
In a conventional wick elevating mechanism, a cylindrical metal wick holder surrounds the substantially whole lower half of the outer periphery of the wick. A rack is attached diagonally to the outer periphery of the wick holder, and a pinion is in mesh with the rack. Thus, the wick is moved up and down by rocking the pinion by means of an operating dial. The wick holder is coupled to the housing of the combustion apparatus by means of metal fittings or pins in order that the rack be securely in mesh with the pinion, and that the wick, as well as the wick holder, be prevented from unexpectedly slipping out of the wick guide cylinder.
Due to the use of the rack and pinion and the metal fittings or pins for coupling, however, these conventional apparatuses are complicated in construction, and require difficult assembly work. With these apparatuses, moreover, it is troublesome to remove and replace tarred wicks.